This invention relates to a catalytic hydrocracking process and a catalyst for use therein. More particularly, the invention relates to a hydrocracking catalyst of improved properties for producing middle distillates and gasoline from heavy gas oils and the like under hydrocracking conditions.
Petroleum refiners often produce desirable products such as turbine fuel, diesel fuel, and other products known as middle distillate (or midbarrel) products, as well as lower boiling products, such as naphtha and gasoline, by hydrocracking a hydrocarbon feedstock derived from a crude oil. Feedstocks most often subjected to hydrocracking are gas oils and heavy gas oils recovered as a fraction from a crude oil by distillation. The typical gas oil comprises a substantial proportion of hydrocarbon components boiling above about 700.degree. F., usually at least about 80% by weight boiling above about 700.degree. F.
Hydrocracking is generally accomplished by contacting, in an appropriate reactor vessel, the gas oil or other feedstock to be treated with a suitable hydrocracking catalyst under suitable conditions of elevated temperature and pressure in the presence of hydrogen so as to yield a product containing a distribution of hydrocarbon products required by (or satisfactory to) the refiner. Although the operating conditions within a hydrocracking reactor are of obvious importance in influencing the yield of product or products, the hydrocracking catalyst is of vital importance in this regard. Many catalysts are known for hydrocracking, but since their respective catalytic properties vary widely, it can be appreciated that hydrocracking catalysts having great usefulness for one purpose, as for example, for maximizing gasoline and naphtha production, are unsuitable for many other purposes, as for example, maximizing the yield of turbine fuel. And even among catalysts useful for producing the same product, the usefulness of each varies according to the requirements of the refiner. For example, a catalyst having high activity for maximum middle distillate (or midbarrel) production under relatively severe conditions may prove inferior for other purposes, as for example, where a relatively large yield of middle distillate product plus a smaller but still significant yield of gasoline is desired from a gas oil feedstock under relatively moderate hydrocracking conditions of elevated temperature and pressure.
The present invention is directed to a catalytic hydrocracking process primarily of advantage in producing a relatively large yield of middle distillate (or midbarrel) products boiling in the 300.degree. to 700.degree. F. range under relatively moderate operating conditions while also producing a significant yield of gasoline.
Accordingly, it is a major object of the invention to provide a catalytic hydrocracking process utilizing a novel hydrocracking catalyst of superior properties for producing a relatively large yield of middle distillate products from gas oils and the like under relatively moderate hydrocracking operating conditions. A more specific object of the invention is to provide a catalytic hydrocracking process for treating hydrocarbon feedstocks boiling primarily above 700.degree. F. so as to produce, under relatively moderate hydrocracking conditions, and in the presence of a superior catalyst, a relatively large yield of middle distillate products boiling between about 300.degree. and 700.degree. F. while concomitantly producing a significant yield of a 185.degree. to 300.degree. F. gasoline fraction. These and other objects of the invention will become more apparent in view of the following description of the invention taken together with the Examples.